Man-machine interfaces have been around since the earliest machines. For early computers, the interface involved a display monitor (e.g., a cathode ray tube—CRT) for providing information to the user, and a textual keyboard for the user to provide input to the computer. Over the years, changes and improvements have been made to simplify this interface. The mouse input device and graphical user interface have made computers much more easy to use, and have become ubiquitous among computers.
Another type of input device has been the electromagnetic tablet, which included a flat surface, under which was an array of antennas that could detect the presence of an electromagnetic pen. As a further improvement on those early tablets, modern tablets have incorporated a display with the tablet's flat surface, so that the computer's display monitor can detect the presence of an electromagnetic pen. Even further improvements have done away with the requirement for the electromagnetic pen, and have become sensitive to the touch of any physical object, such as the user's finger.
All of these advancements and improvements illustrate the general need for simplifying computer-user interfaces, to make computing even easier than before.